Distributed resource scheduler (DRS) is load-balancing solution that assigns and moves computing workloads across available resources in virtualized or cloud environments. Moreover, it optimizes virtual machines (VMs) resource utilization in a server environment. DRS enables users to define the rules for the allocation of hardware resources among virtual machines (VMs) in a platform based on predefined rules called VM affinity rules. In addition, the DRS provides the load-balancing VMs due to imbalanced cluster and VM placement when the servers are powered on. Besides, it may help organizations with automatic load-balancing CPU and storage workloads. The placement of VMs across the cluster is based on vMotion compatibility in the virtualized environment and the vMotion in turn will have its own set of rules or requirements to move the VM workloads across the underlying hosts.
Clustering is grouping of hosts connected to each other with special application that makes them members of a single system in a given environment. Furthermore, there must be a connection of two distinct nodes to create a cluster architecture. Besides, when the hosts are added to the cluster architecture, their resources such as CPU and memory become the resources of the cluster and managed by the cluster controller. Distributed resource scheduler (DRS) and High availability (HA) clusters are typically components of VMware vSphere environments designed to provide high availability to the VMs and services running in the hosts, and load-balancing functions among an ESXi hosts in VMware platforms.